Cyclic mercaptals



United States Patent 3,247,223 CYCLIC MERCAPTALS Edward N. Walsh, Chicago Heights, Ill, and James T. HalletnSaratoga, Calif., assignors to Stanifer Chemical Company, New York, N.Y., a corporation of Delaware No Drawing. Filed June 15, 1962, Ser. No. 202,686 Claims. (Cl. 260327) This invention is directed to a new class of phosphoruscontaining cyclic rnercaptals and acetals, their method of preparation and use as pesticides.

The new compounds of this invention may be represented by the following formula:

wherein R and R are lower alkyl radicals, R is selected from the group consisting of hydrogen and alkyl radicals having from 1 to 5 carbon atoms, R? is selected from the group consisting of methylene and carbonyl, n is an integer from 1 to 2; the groups represented by X are independently selected from the group consisting of oxygen and sulfur, and X and X are independently selected from the group consisting of oxygen and sulfur, at least one of them being sulfur; Y is selected from the group consisting of alkylene radicals having from 1 to 3 carbon atoms and phenylene; and Z is selected from the group consisting of hydrogen and carbethoxy. Suitable alkyl radicals for R and R include methyl, ethyl, propyl, isopropyl, :amyl, octyl, and the like.v

Preparation of the compounds of the present invention is accomplished by reacting a phosphorylated aldehyde or ketone with a glycol or monoor dimercaptan, preferably in the presence of an acid catalyst. This reaction may be represented by the following equation:

wherein R, R R X, X X Y, Z, and n are as described hereinbefore. A solvent such as benzene and ethyl ether may be used but is not strictly essential to the process. Among the suitable acid catalysts for the reaction are boron trifiuoride etherate and gaseous HCl. The reaction may be carried out at temperatures between 0 C. and 100 C. but preferably between about 20 C.

To 24.2 grams of CH C(0)-CH SP(S) (OC H in 8.8 grams of Z-mercapto ethanol was added 4 drops of (C H O-BF A slightly exothermic reaction was observed. The mixture was allowed to stir at a temperature of between 25 and 32 C. for 18 hours, after which time it was transferred to a separatory funnel and extracted with 400 ml. of ether. 'The ether phase containing the product was then washed twice with 500 ml. portions of water and dried over sodium sulfate. After stripping the solvent oil by heating the mixture to 50 C. at 1 mm. of Hg, the product was analyzed and found to contain 26.3 grams (87.0% yield)'of 2-[0,0-diethyl phosphorodithio methyl1-2 methyll,3-oxathiolane, having an index of refraction N 1.5430 and the elemental analysis of 9.6% P and 32.3% S compared to 10.2% P; and 31.8% S, theoretical.

EXAMPLE 2 S SCH2 (CH3O)2PSCH2O CI-I3 O;-CH2 To 12.5 grams of (CH O') P(S)SCH C(O)CH and 4.6 grams of Z-mercapto ethanol was added gaseous HCl.

A vigorous exothermic reaction resulted and H 0 was observed to settle to the bottom of the reaction mixture. After 30 minutes, 100 ml. of benzene was added and the mixture was stirred for about 17 hours. The benzene was then stripped off by heating the mixture to 60 C. at 1 mm. of Hg to yield 15.5 grams (100% yield) of 2- (0,0-dimethyl dithiophosphoromethyl) Z-methyl 1,3- oxathiolane, having an index of refraction N =L5598 and an analysis of 10.5% P and 37.7% S compared to 11.2% P and 35.2% S, theoretical.

Using a procedure substantially in accordance with Examples 1 or 2, the following specific compounds were 2-(0,0-dimethyl phosphorodithio-carbethoxy methyl)- Z-methyl-1,3-oX0thiolane; N =1.5334; yield 13.2 grams percent P:9.l (9.0 theory); percent S=27.8 (27.8 theory). t EXAMPLE 4 S O-CHz II f I (C2H50)2PO-- CH s-oru O,()-dimethyl-O(4-oxo-phenyl) phosphorothioate cyclic ethylene hemithioacetal; N =1.5520; yield=62 grams (93%); percent P=9.3 (9.3 theory); percent S=20.3 (19.2 theory).

EXAMPLE 5 OCH2 ll tonnohPsornon S-CH2 2-(0,0-diethyl phosphorothiomethyl)-1,3-oxathiolane; N =l.5268; yield=12.5 grams (46%); percent P=9.0 (11.4 theory); percent S=27.9 (23.6 theory).

2-(0,0-diethylphosphorothionoethyl) 2-methyl 1,3- oxathiolane; N =1.4975; yield=7.5 grams (86%); percent S=-20.4 (21.4 theory).

EXAMPLE 7 H O--CH2 (ozmonPsoHzcg S-CH2 3 L 2 -(0,0-diethylphosphorodithiomethyl) 1,3 oxathiolane; N =1.5540; yield=20.0 grams (94%); percent P=11.4 (10.8 theory); percent S:33.9 (33.4 theory).

2-(0,0-diethylphosphorodithiomethyl) Z-methyl 1,3- oxathiolane; N :1.5840; yie1d=5.0 grams (32%); percent P=10.0 (9.8 theory); percent S=29.4 (30.3 theory).

2-(0,0-diethylphosphorodithiomethyl) Z-methyl 1,3- dioxalane; N =1.5083; yield=25.0 grams (88%); percent P=11.9 (11.0 theory); percent S=22.9 (22.4 theory) 4 EXAMPLE 14 C53 CiHn 2 methyl-2-(O-methyl-O-butylhosphorodithiomethyl)- 1,3-dithiocyclohexane.

EXAMPLE 15 O-CH2 ll (CzH5 )2P CH2C-CsHn S-CH2 2-amyl 2 (0,0-diethylphosphorodithiomethyl)-1,3- oxathiolane.

Pesticidal activity for the compounds of the foregoing examples is illustrated in Table I wherein the percentage kill is reported for a specified quantity of the candidate pesticide expressed in micrograms (hereafter termed the bio-assay test), or for a percentage concentration in aque- XA 10 E MPLES CH ous dispersion (hereafter termed the screening test). A H a slanted line is used to separate the percentage kill, shown a )2 2 -C s on the left, and the percentage concentraion or quantity,

shown on the right.

Table I Compound House flies, American Milkweed Confused Two-spotted Two-spotted Two-spotted (example number) percent; roach, bug, percent flour beetle, mite post mite eggs, mite systemic,

percent percent emb., percent percent p.p.m.

1 Micrograms.

2-(0,0-dimethy1phosphorodithiomethyl) 2 methyl- 1,3-dithiolane; N =1.5929; yield=24.7 (85% percent P=10.2 (10.7 theory); percent S=43.2 (44.2 theory).

EXAMPLE 11 SOH2 ll (CzH O)zPSCH2C-CH3 SCH2 2-(0,0-diethylphosphorodithiomethyl) 2-methyl-l,3- dithiolane; N :1.5632; yield=24.5 grams (77%); percent P=9.9 (9.8 theory); percent S=38.8 (40.2 theory).

EXAMPLE 12 s-c11, ll (CzH O)zPSCH2C/ CH S-CH2 2.-(0,0-diethylphosphorodithiomethyl) 2 methyl- 1,3-dithiolane; N =1.5371; yield=l6.0 (53%); percent P=9.8 (10.3 theory); percent S=33.2 (31.8 theory). The following new compounds may also be prepared in reasonable yields when using the desired phosphorylated aldehyde or ketone with the corresponding glycol or mercaptan.

EXAMPLE 13 u SC(O) (C4HnO)2PSCH2CCH (1H2 SCH2 2 methyl-2-(0,0-dibutylphosphorodithiomethyl)-1,3- dithio-4-oxo-cyclohexane.

In the screening test for the house fly, M. domestica (Linn); American coackroach, P. americana (Linn.); spotted milkweed bug, O. fasciatus (Dallas); and confused flour beetle, T. confusum (Duval); from 10 to 25 insects were caged in cardboard mailing tubes 3% inches in diameter and 2 /8 inches tall. The cages were supplied with cellophane bottoms and screened tops. Food and water were supplied to each cage, except in the case of the confused fiour beetle which was primarily tested to determine fumigant action. Dispersions of the test compounds were prepared by dissolving /2 gram of the toxic material in 10 ml. of acetone. This solution was diluted with water containing 0.015% Vatsol (a sulfonate-type wetting agent) and 0.005% Methocel (methyl cellulose) as emulsifiers, the amount of water being sufficient to dilute the active ingredients to a concentration of 0.1% or below. The test insects were then sprayed with this dispersion. After 24 and 72 hours, counts were made to determine living and dead insects.

Compounds which showed high mortality in the screening test were bio-assayed on M. domestica. In this test, a known quantity of test compound was placed in a confined area so that it was possible to calculate the exact amount of compound per fly. The same cages were employed as for the screening test. The compound was placed in a 60 ml. petri dish along with 1 ml. of acetone containing light spray oil. After the solution airdried, a cage containing'25 female flies was placed over the residue. Counts of living and dead insects were made after 24 and 72 hours.

The miticidal screening test for the two-spotted mite, T. tetarius (Linn.), involved using young pinto bean plants in the primary stage as host plants. The bean plants were infested with several hundred mites and then sprayed to run-off with an aqueous test dispersion prepared as described above. Sprayed plants were transferred to a greenhouse and held for 14 days. The miticidal and ovicidal activity of the test compounds were determined after 7 to 14 days. The 14 day reading was necessary for evaluating ovicidal action. Percentage mortality is reported, as shown in Table I, for both post embryonic and embryonic forms. In the systemic evaluation of mites, pinto bean plants were placed in bottles containing 200 ml. of the test solution and held in place with cotton plugs. Only the roots were emersed in this solution. The solutions were prepared by dissolving the candidate miticide in acetone or other suitable solvent, and then diluting with distilled water. The final acetone concentration of the solution was never allowed to exceed 1.0% and the compound was initially tested at the concentration of 100 ppm. As soon as the plants had been placed in the solution they were infested with mites. Mortalities of both embryonic and post embryonic forms were ascertained 14 days after initiation of the test.

Although for test purposes aqueous dispersions of the candidate compounds were used, the compounds may also be used in the form of emulsions, non-aqueous emulsions, wettable powders, vapors, and dusts, as may be best suited for the conditions of use. For more specialized applications, the toxic material may even be used in a pure undiluted form.

The term pest is used herein in the restricted sense generally recognized in the art as applying to the lower forms of life customarily controlled .by chemical means and excluding the higher animals, the vertebrates, for example, rodents, birds, and larger forms which are more commonly controlled by mechanical means such as traps. In its broadest usage, the term refers to both the destructive and annoying household and plant organisms, especially .the parasites and pathogens. It will be apparent to one skilled in the art that the activity demonstrated on the selected insects and mites is indicative of activity in various species and orders not specifically shown.

The foregoing description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What we claim is:

"1. A compound of the formula wherein R and R are lower alkyl, R is selected from the group consisting of hydrogen and alkyl having from 1 to 5 carbon atoms, R is selected from the group consisting of methylene and carbonyl, n is an integer from 1 to 2; the groups represented by X are independently selected from the group consisting of oxygen and sulfur, and X and X are independently selected from the group consisting of oxygen and sulfur, at least one of them being sulfur; Y is selected from the group consisting of alkylene having from 1 to 3 carbon atoms and phenylene; and Z is selected from the group consisting of hydrogen and carbethoxy.

2. 2-(0,0-diethylphosphorodithiomethyl) 2 methyl- 1,3-dithiolane.

'3. 2-(0,0 diethylphosphorothiomethyl)-l,3-oxathiolane.

4. 2-(0,0-diethylphosphorodithiomethyl) 2 methyl- 1,3-oxathio1anc.

'5. 2 (0,0-dimethylphosphorodithiomethyl)-2-methyl- 1,3-oxothiolane.

References Cited by the Examiner UNITED STATES PATENTS 2,701,253 2/1955 Jones et al. 260327 2,789,124 4/1957 Gilbert et al. 260--461.112 2,815,350 12/1957 Speck 260-327 2,853,416 9/1958 Kellog 167-33 2,920,997 1/1960 Wolf et al. 167-33 3,053,852 9/ 1962 Coover et al. 260-327 3,071,594 l/l963 Enders et al. 260-327 FOREIGN PATENTS 510,817 5/1952 Belgium.

OTHER REFERENCES Djerassi et al., J our. Amer. Chem. Soc., vol. (1953), pages 3704-8.

The Naming and Indexing of Chemical Compounds by Chemical Abstracts (Introduction to the 1 945 Subject Index), December 1947, page 5955.

WALTER A. MODANCE, Primary Examiner.

NICHOLAS S. RIZZO, Examiner. 

1. A COMPOUND OF THE FORMULA 